Calcium Carbide: My teachers are wondering whether there are any restrictions on us storing and using Calcium carbide for pracs here at school? They apparently used to do some wonderful pracs with it in the past, which they have not done for many years, however I am concerned about the safety of these pracs.
Submitted by sat on 24 September 2017
Answer reviewed 27 January 2023
Calcium carbide can be safely stored with Dangerous Goods Class 4.3, segregated from incompatible chemicals, and MUST be kept dry.
When calcium carbide reacts with water it forms acetylene gas (ethyne) and calcium hydroxide, and generates heat.
CaC2 (s) + 2H2O (l)→ C2H2 (g) + Ca(OH)2 (s)
Calcium carbide may contain impurities of phosphorus, nitrogen and sulfur compounds. While pure acetylene gas is odourless and non-toxic, these impurities in the calcium carbide, when reacted with water, produce trace amounts of phosphine, ammonia and hydrogen sulfide, which are toxic and can impart an unpleasant odour to the gas. Acetylene can form explosive mixtures with air.
Calcium carbide is not banned from use; however, the following safe practices should be observed:
DO NOT:
Recommended activity:
A safe alternative is to view the following videos:
‘Calcium Carbide & Acetylene - Periodic Table of Videos’, YouTube (6:20 min), https://youtu.be/KQSLpuVZK9Y (7 May 2012)
Chem Supply website, (2022) ‘Safety Data Sheet’. Please search the product information page on the website for the latest version for calcium carbide https://shop.chemsupply.com.au/
Queensland Department of Education, Training and Employment. 2014. Unpredictable science experiments. Health & Safety Alert, DET website, https://education.qld.gov.au/initiatives-and-strategies/health-and-wellb... (Search for Unpredictable science experiments)